This invention relates generally to the field of disc drive data storage devices, and more particularly but not by way of limitation, to a disc snubber for protecting discs from damage due to nonoperational mechanical shocks.
Hard disc drives enable users of computer systems to store and retrieve vast amounts of data in a fast and efficient manner. In a typical disc drive, the data is magnetically stored on one or more discs which are rotated at a constant high speed and accessed by a rotary actuator assembly having a plurality of read/write heads that fly adjacently the surfaces of the discs.
The heads are suspended from gimbal assemblies extending from arms of the rotary actuator assembly and include aerodynamic features that enable the heads to fly upon an air bearing established by air currents set in motion by the rotation of the discs. When the disc drive is deactivated, a shutdown operation is commenced wherein the heads are moved to a safe parking position before the discs come to a stop.
It is a continuing trend in the disc drive industry to provide disc drives with ever increasing data storage capacities using the same or a smaller form factor (i.e., outside dimensions) for the drives. As a result, successive generations of drives are often provided with discs that are closer together, reducing disc to actuator arm clearances. At the same time, disc drives are being utilized in harsher environments, such as portable computers, requiring increases in the robustness characteristics of the drives so as to withstand ever greater external vibrational and shock input levels. For example, a typical disc drive might be required to withstand up to a 200 g mechanical shock in a nonoperating mode.
Such mechanical shocks can cause significant deflection of the discs, leading to catastrophic damage to the disc media and heads. More particularly, disc to actuator arm contact can induce a shock wave large enough to travel down to the gimbal assemblies and heads, causing the heads to flex up off of the landing zones as a result of the relatively flexible gimbal assemblies to which the heads are attached. The heads can thus obtain significant velocities as they accelerate away from and then back toward the discs. When such velocities are sufficiently severe, damage can occur to the heads and the surfaces of the discs as the heads strike landing zones. Moreover, should a head tilt during such liftoff, a corner of the head can strike the disc surface, increasing probability of damage to the head or the disc.
Disc snubbers such as disclosed in the U.S. Pat. No. 5,422,770 issued Jun. 6, 1995 to Alt have been taught in the prior art in an attempt to limit the deflection of the discs of a disc drive subjected to large nonoperational shocks. However, it has been observed that localized snubbers such as disclosed by the Alt patent could be displaced upon application of a mechanical shock. Other attempts have been made in which isolators have been mounted by screws. Screws occupy significant space and create added cost and time in assembly and installation. In a relatively small computer such as a laptop, where space is limited, the added cost of assembly and installation of extra pieces defeats the purpose of a low cost, space efficient computer.
Accordingly, there is a need for an improved approach to minimizing damage to a disc drive as a result of nonoperational shock by limiting the ability of the discs to contact the arms of an actuator of the disc drive.
The present invention provides an apparatus and method for minimizing damage to a disc drive subjected to nonoperational mechanical shock.
In accordance with a preferred embodiment, the disc drive comprises a plurality of discs having data recording surfaces, a spindle motor for rotating the discs about a central axis and an actuator assembly supporting a plurality of controllably positionable heads adjacent the recording surfaces.
A disc snubber is disposed within a snubber aperture in the actuator assembly, and is disposed to nest the disc perimeters when the actuator assembly is in its head park position. The disc snubber comprises a body portion adapted to snugly fit within the snubber aperture, and a plurality of bumper arms extend radially from the body portion toward the actuator arms so that the bumper arms extend above and below the discs during non-operation. Furthermore, the bumper arms are coextensive with the actuator arms for a distance that provides protection from disc to actuator arm contact during disc deflection resulting from nonoperational shock while providing clearance during disc rotation.
The method of making the disc snubber comprises providing a snubber aperture through the actuator assembly, providing a rod of sufficiently rigid snubber material to be disposed with a snug fit in the snubber aperture, disposing the snubber material in the aperture, securing the rod of snubber material in the snubber aperture and machining the snubber material to form the bumper arms.
These and various other features as well as advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.